Idler group and method of assembly

ABSTRACT

An idler group is disclosed for a mobile machine having a tracked undercarriage with an endless track. The idler group may include a retainer disposed on an axle and within an opening in an idler. The retainer may be configured to achieve an interference fit with the idler sufficient to hold the retainer within the opening of the idler during operation of the mobile machine. In another embodiment, a retaining ring may be disposed within a channel formed in the idler and may contact the retainer. In yet another embodiment, a swaged connection may be formed between the idler and the axle.

TECHNICAL FIELD

The current disclosure relates generally to a mobile machine, and moreparticularly to an idler group and a method of assembling an idler groupfor a track-type mobile machine.

BACKGROUND

A mobile machine may be used to perform various types of work ondifferent worksites, such as a construction site, a demolition site, amining site, or a landfill site. For example, a bulldozer may be used topush soil and rock on a construction site. The bulldozer, as atrack-type mobile machine, may include a tracked undercarriage withtracks on the left and right sides of the machine. Each of the tracksmay include a chain formed by connecting a number of track links to oneanother, and connecting a number of track shoes to the chains. Thetracks are supported by various roller assemblies on both sides of themachine, including idler groups that guide the tracks.

FIGS. 1 and 2 show an example of a known idler group 100. As illustratedin the drawings, idler group 100 includes an idler 102, which istypically formed of multiple components welded to one another. Idler 102includes a rim 104 that is sized and shaped to engage and guide thetrack links. Idler group 100 also includes an axle 106, radial andthrust bearings 108 and 110 (only shown in FIG. 2), and end caps 112,among other components. Each end cap 112 is attached to idler 102 bymultiple bolts 114, so that idler 102 is able to rotate on the bearingswhile being retained on axle 106.

Use of the known idler group results in numerous disadvantages, however.For example, assembly and disassembly of the idler group is laborintensive and expensive due to the number of bolts used to attach theend caps to the idler. Further, vibrations experienced by the idlergroup may result in the bolts loosening, so that the end caps are nolonger reliably attached to the idler.

Thus, there exists a need for an improved idler group. The idler groupand method of assembly in accordance with the current disclosure mayovercome or avoid disadvantages resulting from the use of theabove-described or other known idler groups.

SUMMARY

The current disclosure may provide an idler group for a mobile machinehaving a tracked undercarriage with an endless track. The idler groupmay include an idler configured to guide the endless track. An axle maybe disposed through a central opening in the idler and configured topermit the idler to rotate relative to the axle. A retainer may bedisposed on the axle and within an opening in the idler. The retainermay be configured to achieve an interference fit with the idlersufficient to hold the retainer within the opening of the idler duringoperation of the mobile machine.

The current disclosure may further provide an idler group for a mobilemachine having a tracked undercarriage with an endless track. The idlergroup may include an idler configured to guide the endless track. Anaxle may be disposed through a central opening in the idler andconfigured to permit the idler to rotate relative to the axle. Aretainer may be disposed on the axle and within an opening in the idler,the retainer configured to achieve an interference fit with the idler. Aretaining ring may be disposed within a channel formed in the idler andmay contact the retainer.

The current disclosure may still further provide an idler group for amobile machine having a tracked undercarriage with an endless track. Theidler group may include an idler configured to guide the endless track.An axle may be disposed through a central opening in the idler to permitthe idler to rotate relative to the axle. A retainer may be disposed onthe axle and within an opening in the idler, the retainer configured toachieve an interference fit with the idler. A swaged connection may beformed between the idler and the axle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an isometric view of a known idler group;

FIG. 2 illustrates a cross-sectional view of the known idler group ofFIG. 1;

FIG. 3 illustrates an isometric view of a bulldozer including an idlergroup consistent with the disclosure; and

FIG. 4 illustrates a cross-sectional view of the idler group of FIG. 3.

DETAILED DESCRIPTION

FIG. 3 illustrates a mobile machine 10 with a chassis 12 having atracked undercarriage 14, consistent with the disclosure. As shown inFIG. 3, machine 10 may be a bulldozer, and may include a blade 16pivotally supported from chassis 12. Blade 16 may be configured to push,dig, pick up, transport, or otherwise move soil, rock, constructionmaterials, debris, and the like on a worksite. Machine 10 may alsoinclude an implement 18, such as a ripper for breaking up the surface ofthe worksite. Machine 10 is not limited to being a bulldozer, however,but may be any machine that includes a tracked undercarriage. Further,whether or not machine 10 is a bulldozer, machine 10 is not limited toincluding either or both of blade 16 and implement 18, but instead mayinclude other tools (e.g., a bucket, a shredder, etc.) or may entirelyomit either or both of blade 16 and implement 18.

Tracked undercarriage 14 may be configured to support machine 10 andmove the machine along the ground, roads, and/or other types of terrain.As shown in FIG. 3, undercarriage 14 may include a track roller frame22, various guiding components connected to track roller frame 22, andan endless track 24 that engages the guiding components. The guidingcomponents of the undercarriage 14 may include a drive sprocket 26,idler groups 28, and rollers 30, which are discussed in further detailbelow.

Track 24 may include a link assembly 32 that forms a flexible backboneof track 24, as well as a plurality of shoes 34 secured to link assembly32. Link assembly 32 may include a plurality of links 36 connected toone another at pivot joints 38. In FIG. 3, only half of links 36 of linkassembly 32 may be seen. For each link 36 visible in this figure, linkassembly 32 includes a corresponding laterally spaced link 36. Linkassembly 32 may form an endless chain that extends around and encirclesdrive sprocket 26, idler groups 28, and rollers 30, among othercomponents. Shoes 34, which are configured to contact a ground surfaceunderneath machine 10, may be secured to an outer perimeter of linkassembly 32.

As shown in the configuration of FIG. 3, rollers 30 may be installed onthe lower side of track roller frame 22 and thus may guide the lowerportions of track 24. For example, each roller 30 may be rotationallysupported on an axle 40 that is suspended below track roller frame 22.Rollers 30 may ride on and guide links 36 in the lower portion of theendless chain that is formed by link assembly 32. Although not includedin the configuration shown in FIG. 3, rollers may be used to guide theupper portions of track 24. In such an arrangement, the rollers may beconnected to the upper side of roller frame 22, such that links 36 inthe upper portion of the endless chain ride on the rollers.

Drive sprocket 26 and idler groups 28 may also guide portions of track24. Idler groups 28 may be connected to opposite ends of track rollerframe 22, and drive sprocket 26 may be connected above roller frame 22closer to one idler group 28 and a back end of machine 10. The endlesschain formed by link assembly 32 may wrap around drive sprocket 26 andidler groups 28. One or more portions of drive sprocket 26 may projectinto spaces between laterally spaced pairs of links 36. As described inmore detail below, one or more portions of each idler group 28 mayproject into spaces between laterally spaced pairs of links 36. Drivesprocket 26 and idler groups 28 may rotate about lateral axes to guidethe ends of link assembly 32 through approximately semicircular pathsbetween the lower and upper portions of the endless chain formed by linkassembly 32. Additionally, because they extend into spaces betweenlaterally spaced pairs of links 36, sprocket 26 and idler groups 28 mayguide link assembly 32 in lateral directions. Sprocket 26 may be rotatedby an external power source (not shown) of machine 10, such as anengine, to thereby move link assembly 32. Driven by sprocket 26, linkassembly 32 may, in turn, rotate idler groups 28 as well as rollers 30around their respective rotational axes. In the arrangement shown inFIG. 3, drive sprocket 26 is elevated above the ground at a heighthigher than that of each idler group 28, which are at a same height asone another. In alternate embodiments, however, drive sprocket 26 may beelevated at a height above the ground which is approximately the same asthat of idler groups 28, or lower than that of idler groups 28. Further,although idler groups 28 are shown as being disposed at a same heightabove the ground, one idler group 28 may be disposed at a differentheight than one or more other idler groups 28.

Although FIG. 3 shows specific examples of components that may beincluded in machine 10 and in tracked undercarriage 14, idler groups 28are not required to be used with a machine or undercarriage thatincludes any or all of these particular components. For example, idlergroup 28 may be used with a tracked undercarriage that includes more orfewer components, or other components, such as different numbers and/ortypes of rollers, as well as different types of track guidingmechanisms. Further, consistent with the disclosure, trackedundercarriage 14 is not required to include two idler groups 28 on eachside of machine 10, but instead may include only one idler group 28 oneach side.

FIG. 4 shows an exemplary embodiment of one idler group 28 from FIG. 3.As shown in FIG. 4, idler group 28 may include an idler 42 and an axle44. Specifically, axle 44 may be disposed through a central opening ofidler 42, so that idler 42 may rotate relative to axle 44. Idler 42 maybe formed from a hub 46 that is connected to a body 48. Hub 46 may beconstructed of two pieces that are connected to one another, such as bybeing welded together at a middle portion of each piece. Body 48 may beconstructed so as to be hollow with a cavity 50 inside it. For example,body 48 may be formed from two side plates 52 and a rim 54. Each sideplate 52 may be a frustoconical disc that is connected to hub 46, suchas by being welded to hub 46. Side plates 52 may diverge away from oneanother as they extend radially outward from hub 46. Rim 54 may beconnected to side plates 52, such as by welding. Rim 54 may be formed soas to include a center flange 56 that is flanked by a pair of treadshoulders 58. In operation, center flange 56 may be disposed betweenlinks 36 (shown in FIG. 3) of the endless chain, while tread shoulders58 may ride directly on links 36. One or more of idler 42, axle 44, hub46, and body 48 may be made of metal, such as high-carbon steel oranother type of steel. Although FIG. 4 shows a specific example of idler42, idler 42 is not limited to the specific configuration illustrated inthe drawing. For example, idler 42 may be constructed of more or fewerparts, and the parts may be connected by processes other than welding.Consistent with the disclosure, idler 42 alternately may be constructedas a unitary component from a single piece of material, such that nojoining of parts occurs during manufacture of idler 42, but insteadidler 42 may be formed entirely by material removal and reshapingprocesses.

Idler group 28 may include radial and thrust bearings 62 and 64 that aredisposed between axle 44 and idler 42. By this arrangement, idler 42 maybe permitted to rotate on and relative to axle 44. Idler group 28 mayfurther include a retainer 66 on each side thereof to form connectionsbetween retainers 66 and idler 42 on axle 44. Specifically, retainers 66may be disposed on axle 44 and within openings in idler 42. Thus,retainers 66 may serve to locate and retain idler 42, as well as radialand thrust bearings 62 and 64, on axle 44. Each retainer 66 may be inthe form of a ring, and may be sized and shaped to provide aninterference fit between retainer 66 and idler 42. The interference fitmay be sufficient to hold retainer 66 within idler 42 during operationof machine 10 on a worksite, without requiring the use of separatefasteners (e.g., bolts) to connect retainer 66 and idler 42. Forexample, retainer 66 may include an outer portion 68, which has an outerdiameter slightly larger than a corresponding inner diameter of an innerportion 70 of idler 42. Outer portion 68 and inner portion 70 may becylindrical surfaces and may extend in a direction approximatelyparallel to the rotational axis of axle 44.

Retainer 66 may also include a bottom portion 72 that is configured tocontact a top portion 74 of idler 42. Each of bottom portion 72 and topportion 74 may be an approximately flat surface. By this arrangement,when bottom portion 72 contacts top portion 74, retainer 66 may be fullyseated within idler 42. Bottom portion 72 and/or top portion 74 mayextend in a direction that is approximately perpendicular to therotational axis of axle 44, and thus may be approximately perpendicularto the direction in which outer portion 68 and inner portion 70 extend.Retainer 66 may be made of metal, such as high-carbon steel or anothertype of steel.

Consistent with the disclosure, retainer 66 is not limited to thespecific form shown in FIG. 4. For example, retainer 66 may be shapedfor easy insertion into or removal from idler 42. Retainer 66 also mayhave other surfaces, contours, openings, and the like, such as to locateor retain other components on axle 44 or within idler group 28 (e.g., tohold a fluid seal installed between idler 42 and retainer 66, such aseal being installed in channels formed in either or both of innerportion 70 of idler 42 or outer portion 68 of retainer 66). Retainer 66may be formed from a single piece of material through material removalprocesses, or instead may be formed from multiple pieces that areconnected to one another, such as by welding.

Although not required, one or more surfaces of retainer 66 and/or idler42 may include elements that aid in the retention of retainer 66 withinidler 42 by increasing the frictional force resulting from theinterference fit therebetween. For example, either or both of outerportion 68 of retainer 66 and inner portion 70 of idler 42 may be atleast partially textured, such as by knurling. This texturing may act toincrease the frictional force between retainer 66 and idler 42, therebyproviding a larger frictional force as compared to a similarly sizednon-textured surface. Alternately or additionally, either or both ofouter portion 68 of retainer 66 and inner portion 70 of idler 42 may beat least partially threaded, the threads cooperatively engaging oneanother. Cooperatively engaging threads 71 are illustrateddiagrammatically in FIG. 4.

Optionally, idler group 28 may include a retaining ring 76 that aids inholding retainer 66 within idler 42. As shown in FIG. 4, retaining ring76 may be disposed within a channel 78 that is formed in a portion ofidler 42, such as within inner portion 70 of idler 42, and a surface ofretaining ring 76 may be in contact with a portion of retainer 66. Whenretaining ring 76 is used, retainer 66 may still be held within theopening of idler 42 although the interference fit between idler 42 andretainer 66 may provide a lesser frictional force. For example, thedifference between the outer diameter of outer portion 68 and the innerdiameter of inner portion 70 may be smaller than compared to theconfiguration that does not use retaining ring 76. Thus, even if theinterference fit between idler 42 and retainer 66 would not besufficient by itself to hold retainer 66 within idler 42 duringoperation of machine 10 on a worksite, the addition of retaining ring 76may be sufficient to hold retainer 66 within idler 42, thus resulting inan arrangement that may omit the use of other fasteners (e.g., bolts)connecting retainer 66 and idler 42. Retaining ring 76 may be formedfrom metal, such as steel. Although FIG. 4 shows a specific example ofretaining ring 76, retaining ring 76 is not limited to the particularring illustrated in the drawings, and may have a different shape, or maybe formed from multiple components.

Also consistent with the disclosure, retainer 66 and idler 42 may beswaged together. Swaging may occur at a discrete number of positions(e.g., 4 positions, or 8 positions) along a circumference of aninterface between retainer 66 and idler 42, or swaging may occur alongapproximately the entire circumference of the interface between retainer66 and idler 42. The material of idler 42, retainer 66, and/or adifferent component may be swaged into one or more openings in idler 42and/or retainer 66. When idler group 28 is swaged, retainer 66 may stillbe held within the opening of idler 42 although the interference fitbetween idler 42 and retainer 66 may provide a lesser frictional force.For example, the difference between the outer diameter of outer portion68 and the inner diameter of inner portion 70 may be smaller thancompared to the configuration that does not include a swaged connection.Thus, even if the interference fit between idler 42 and retainer 66would not be sufficient by itself to hold retainer 66 within idler 42during operation of machine 10 on a worksite, swaging idler 42 andretainer 66 may result in an arrangement that may omit the use of otherfasteners (e.g., bolts) to connect retainer 66 with idler 42.

INDUSTRIAL APPLICABILITY

Thus, the foregoing description describes an exemplary configuration ofidler group 28, including a connection between idler 42 and retainer 66,as well as an example of a particular machine 10 that may include idlergroup 28. However, idler group 28 is not limited to use in theparticular machine shown in the drawings, but instead may be used withother various machines or structures.

Consistent with the disclosure, idler group 28 may include a connectionbetween idler 42 and each retainer 66, such that idler 42 may besecurely retained on axle 44. As a result of the interference fitbetween idler 42 and each retainer 66, whether with or without the useof retaining ring 76 or a swaged connection, each retainer 66 may beheld in the opening of idler 42.

Thus, idler group 28 in accordance with the present disclosure providesnumerous advantages compared to known idler groups. For example, idlergroup 28 does not require the use of multiple fasteners, such as bolts,which are required to connect both end caps to the idler in the knownconfiguration. Rather, the interference fit between retainer 66 andidler 42 may be sufficient to maintain the connection therebetweenduring operation of machine 10 on a worksite. Therefore, the time andexpense associated with installing multiple fasteners for each end capare avoided. Further, attachment of retainer 66 to idler 42, when usedwith retaining ring 76, may require no specialized tooling such as animpact wrench and an associated air delivery system and relatedcomponents (hoses, pressure regulators, etc.). Instead, retainer 66 maybe inserted into retainer 42 by hand, and retaining ring 76 also may beinstalled by hand. Still further, when idler group 28 includes a swagedconnection between idler 42 and retainer 66, the interference fittherebetween may be sufficient to securely hold retainer 66 in idler 42during swaging, such that a precise connection may be formed betweenidler 62 and retainer 66.

It will be apparent to those skilled in the art that variousmodifications and variations may be made to the disclosed idler group.Other embodiments of the described idler group will be apparent to thoseskilled in the art from consideration of the specification and practiceof the assembly and method disclosed herein. Thus, it is intended thatthe specification and examples be considered as non-limiting.

What is claimed is:
 1. An idler group for a mobile machine having atracked undercarriage with an endless track, the idler group comprising:an idler configured to guide the endless track; an axle disposed througha central opening in the idler and configured to permit the idler torotate relative to the axle; and a retainer disposed on the axle andwithin an opening in the idler, the retainer configured to achieve aninterference fit with the idler sufficient to hold the retainer withinthe opening of the idler during operation of the mobile machine; whereinthe idler includes an inner surface having an inner diameter, theretainer includes an outer surface having an outer diameter greater thanthe inner diameter, both of the outer and inner surfaces includingthreads that cooperatively engage each other, and the outer and innersurfaces contact one another to achieve the interference fit when theretainer is disposed within the opening of the idler.
 2. The idler groupof claim 1, wherein at least one of the outer surface or the innersurface includes a textured surface.
 3. The idler group of claim 1,further including: radial and thrust bearings disposed on the axlebetween the axle and the idler.
 4. The idler group of claim 1, whereinthe idler includes a top surface, the retainer includes a bottomsurface, and the top and bottom surfaces contact each other when theretainer is disposed within the opening of the idler.
 5. The idler groupof claim 4, wherein the top and bottom surfaces are approximately flatplanar surfaces extending in a direction approximately perpendicular toa rotational axis of the axle.
 6. The idler group of claim 5, furtherincluding: radial and thrust bearings disposed on the axle between theaxle and the idler.
 7. An idler group for a mobile machine having atracked undercarriage with an endless track, the idler group comprising:an idler configured to guide the endless track; an axle disposed througha central opening in the idler and configured to permit the idler torotate relative to the axle; a retainer disposed on the axle and withinan opening in the idler, the retainer configured to achieve aninterference fit with the idler; and a retaining ring disposed within achannel formed in the idler and contacting the retainer; wherein theidler includes an inner surface having an inner diameter, the retainerincludes an outer surface having an outer diameter greater than theinner diameter, both of the outer and inner surfaces include threadscooperatively engaging one another, and the outer and inner surfacescontact one another when the retainer is disposed within the opening inthe idler.
 8. The idler group of claim 7, wherein at least one of theouter surface or the inner surface includes a textured surface.
 9. Theidler group of claim 7, further including: radial and thrust bearingsdisposed on the axle between the axle and the idler.
 10. The idler groupof claim 7, wherein the idler includes a top surface, the retainerincludes a bottom surface, the top and bottom surfaces are approximatelyflat planar surfaces extending in a direction approximatelyperpendicular to a rotational axis of the axle, and the top and bottomsurfaces contact one another when the retainer is disposed within theopening in the idler.
 11. The idler group of claim 10, furtherincluding: radial and thrust bearings disposed on the axle between theaxle and the idler.